1. Field of the Invention
This invention involves a low vacuum high-speed method for oil/water separation for mixture liquids or emulsions liquids of oil and water, as well as a device for purification of oil for low vacuum separation of oil/water and oil/gas, mainly used in industrial oils: the refinement of fresh oils as well as the recovery, regeneration and refinement of industrial waste oils.
2. Description of Related Art
With the speedy development of science, technology and industries, the demands of the degree of purification and refinement for industrial oils, such as lubrication oils, hydraulic pressure oils, and transformer oil, are becoming increasingly strict and the amount of oils consumed also grows daily. Subsequently, in industries, the refinement of fresh oils not only has to be up to the stipulated standards, but the discarding of waste oils is not permissible by environmental laws and the law on the utilization of resources as well. Furthermore, this is also impractical in consideration of production cost. Thus, the recovery, refinement and regeneration of huge amounts of waste oils are involved; the waste oils are made to reach the stipulated standards for use. In addition, when being used, the oils are also being contaminated at a high speed. Therefore, for oils in the process of being used, continuous purification is also needed to ensure normal operation of the equipment.
In the process of being used, contamination of the oils can produce great damage. For example, in hydraulic pressure systems, the rate of accidents caused by the contamination of oils can reach as high as 82%, while for electric and mechanical systems, only 18%. When transformer oils become off standard, the transformer will be in danger of being punctured.
The most harmful contaminants in oils are: water, gases, solid particles, and the like among which water can reduce the viscosity of the oils, thus making the oils out of conformity with the usage demand, water can also lower the membrane strength of the oils or break the oil membrane, resulting in accelerated wear and tear of the equipment; water and air can make the requisite chemical additives in oils become ineffective, producing acidic substances and speeding up the aging of the oils. While in operation, the life span of waterless transformer oil is 5.6 times that of water-containing transformer oil. As for hydraulic pressure systems, water and air enhance the gas hole phenomenon, thus affecting the stability, increasing the vibration and noises of the system, shortenting the life span of the equipment, and even creating accidents.
The water in oils is not only very harmful, but to separate it from the oils is also rather difficult. For oils with higher viscosity, when oil and water mixes, and when the mixture undergoes agitation during the equipment's operation, the mixture rapidly emulsifies; separation of the water from the oils at this state is even more difficult, especially the oils containing various chemical additives. The additives strengthen the oil/water emulsification, and this enhances the difficulties of separation. For example, there has not been a good device up to the present that can quickly separate the water from the hydraulic pressure oil. Besides, in the field of the purification of oils, the purification is usually being conducted by adopting chalk, silica gel, or activated carbon. However, when the water content is high, water can quickly render these absorbents ineffective. Therefore, it is necessary to first eliminate the greater part of the water.
Thus, the separation of oil/water is both very important and very difficult. The technology of low vacuum separation of oil/water and oil/gas as well as well as of the purification of oil has long been emphasized by people in the field of industry. There are many conventional devices in this respect, most adopting methods like these: pass the oil/water mixture (including emulsion) liquid through the spray element which is deposited at the top of the vacuum container or column, spray it into fine drops, then fall onto the filler or grid at the lower part, thus increasing the areas of interface of the two gas/liquid phases of the liquid, at the same time the resulting droplets are obstructed by the filler, thus prolonging the retaining periods of the liquid droplets or the thin liquid layers in space. The chances for the evaporation of the water in the oil are thus increased. Because the saturated steam pressure of the oil is very low, under this state, the oil evaporates very little, resulting in the gas and part of the water being separated under a low pressure, thus achieving the goal of oil/water separation and oil/gas separation. Finally, the oil or oil/water liquid falls to the lower part of the container, which is pumped or extracted to enter into the spray element again for recycle dewatering.
From the theory of mass transfer, it is known that the separation of oil/water is actually the evaporation of one component that is easier to evaporate in a two component mixture liquid. Under definite temperature or pressure (or in vacuum), it is required that the liquid possess the biggest possible interface areas of the two gas/liquid phases, therefore, the longer the liquid droplets or the liquid thin layers remain in the gaseous phase the better, the two gas/liquid phase interfaces should speedily renew. Only thus can the water in the oil/water mixture liquid be quickly separated out of the mixture. However, in the above conventional method using spray and filler there exist the following deficiencies: First, the capability of the spray plus filler to increase the interfaces of the two phases of liquid/gas is limited; second, the capability of the filler in obstructing, thus delaying the liquid from falling is even more limited; third, as the viscosity of oil increases, the surface of the oil is difficult to be renewed. These three factors limit the oil/water separation speed of the above conventional method.
The object of this invention is to provide a new method for the separation of oil and water, which differs from the conventional method in that oil and water can be rapidly separated under the same temperature and absolute pressure (vacuum); it also provides low vacuum oil/water separation, oil/gas separation using said method, as well as a device for the purification of oil.